Metabolic Bone Disease

Question 1

Learning Outcome:

Answer 1

1. Osteoporosis
2. Osteomalacia
3. Rickets
4. Hyperparathyroidism

Question 2

Osteoporosis pathology

Answer 2

1. Risk factor
   i. non-modifiable
   - age, female, premature menopause
   ii. modifiable
   - smoking, alcohol, low calcium diet, sedentary lifestyle
2. Type
   i. primary osteoporosis
   - postmenopausal (estrogen def)
   - involutional (ageing, chronic illness)
   - postclimacteric (androgen def)*15 yrs later
   ii. secondary
   - endocrine (cushing, hypogonadism, thyrotoxicosis)
   - drugs (glucocorticoids, heparin, anticonvulsant)
   - chronic disease (renal impairment, liver cirrhosis)
   - malignancy
3. Common fracture site
   - wrist
   - hip
   - spine

Question 3

Osteoporosis diagnosis

Answer 3

Hx

• Back pain
• Risk factor

Pe

• anterior chest wall collapse
• hyperkyphosis (dowager’s hump)
• reduced height

Ix

• TFT
• FSH, LH
• Urine bence jones
• Serum protein electrophoresis

X-Ray

• generalised lucency
• codfish vertebrae (biconcave)

Bone Densitometry

• Gold standard
• measure at L2-L4, femoral neck, trochanter, intertrochanter
• diagnosis: T-score: less than -2.5

Question 4

Osteoporosis management

Answer 4

Prophylaxis

1. Nutrition
2. Exercise
3. Hip protectors

Pharmacology

1. HRT
2. Biphosphonate (bone resorption inhibitor)
   * cannot give if there is fracture, cause delay healing
3. Recombinant PTH
4. Selective endrogen receptor modulation (SERMs)

Surgical

1. Hip:
   - Conservative discouraged
   - Risk of sores, dvt development
2. Vertebral:
   - most fracture stable
   - intervention needed when there is nerve root or spinal cord fracture

Question 5

Rickets pathology

Answer 5

1. Type of rickets
   i. Familial hypophostphatemic (vit-d resistant)
   ii. Nutritional (vit-d deficient)
   iii. Renal osteodystrophy

Question 6

Rickets diagnosis

Answer 6

Pe

• delay fontanelle closure
• frontal bossing
• dental hypoplasia
• leg bowing
• tetany or convulsion

Ix

• serum calcium, phosphate
• LFT
• bone biopsy

Question 7

Hyperparathyroidism pathology

Answer 7

1. Type
I. primary
- adenoma (85%)
- hyperplasia
ii. secondary 
- osteomalacia
- rickets

Question 8

Hyperparathyroidism diagnosis

Answer 8

Hx
- git: nausea, abdominal pain

Ix

i. blood: serum calcium, phosphate, pth
ii. urinalysis
iii. imaging: osteoporosis, brown tumour lesion, subperiosteal reaction of middle phalanx

Question 9

Hyperparathyroidism management

Answer 9

Conservative

• adequate hydration
• avoid high calcium products

Question 10

Paget’s Disease pathology

Answer 10

• increase bone turnover
• abnormal internal bone architecture
• enlargement and bone thickening